Now Cuban has put his lawyers where his mouth is, with a subpoena in federal court in his Texas stronghold. Magnolia Pictures, a film distributor which he owns with investment partner Todd Wagner, is demanding Google reveal details of users who uploaded clips of its movies, which include documentaries Enron: The Smartest Guys in the Room and Capturing the Friedmans.

The subpoena demands Google hand over the details by March 20. Google deployed its standard wall of silence in response to its legal department's latest project.

Cuban has already made it clear the filing is less about witchfinding individuals, and more about making a point to Google. He told Reuters today: "We don't expect to get valid user information. If we do, we will contact them and ask them what induced them to upload content they don't own."

Fox shot across YouTube's bows with similar legal posturing in January. Its subpoena identified one user in particular, who had uploaded Simpsons and 24 episodes.

Just as Cuban's subpoena can be viewed as a noise-making exercise, Fox's move was most usefully interpreted in the context of the ongoing battle for ads and eyeballs between media and tech giants. ®